For example, a printed board is produced via a step of etching a metal foil of a laminate having a metal foil layer (such as copper foil) as a conductive layer laminated on an insulating layer (such as a polyimide) to remove unnecessary portions and thereby to form a patterned circuit.
Heretofore, an epoxy resin, an acrylic resin or the like has been used as an adhesive for an insulating layer and a metal foil layer or insulating layers each other, however, it has been studied to use a fluorinated resin which is excellent in electric properties in order to improve the electric reliability of a printed board.
Patent Document 1 discloses a process for producing a laminate for a printed board, which comprises between two laminated films wherein a conductive layer is laminated on a non-thermoplastic aromatic polyimide resin layer, sandwiching a fluorinated resin film so as to be in contact with the polyimide resin layer, followed by press bonding under a heating atmosphere.
According to this method, a laminate having a structure wherein the polyimide resin layers are laminated on both surfaces of the fluorinated resin layer, can be obtained.